1. Field of the Invention
The present invention relates to a missile launcher sight, and more particularly to a sight having an image intensifier providing night vision capability for use with hand held missile launchers.
2. Description of the Prior Art
The STINGER Man Portable Air Defense System (MANPADS) is a shoulder launched anti-aircraft missile which has been produced in large quantities by several manufacturers. The STINGER launcher utilizes an open sight similar to the "iron sights" on a rifle in daylight conditions (day sight) for "acquiring" aircraft targets, i.e., aiming the launcher to enable the missile's guidance system to sense and track ("lock on to") a target. The day sight, like a standard rifle sight, has a rear aperture or "peep sight" and a front aperture. To acquire a target, the front and rear apertures are aligned with the target and the missile's heat seeking guidance system is activated. Once the target is acquired and locked on to, the front sight has further alignment features which the gunner uses to elevate the launch tube and adjust for proper lead angle prior to launching the missile. The lead angle is the angular displacement of the launcher from a position of pointing at the target to a position of pointing forward of the target in its direction of movement. The object of aiming forward of the target is to allow the missile to meet the target using the shortest trajectory possible. The sight assembly described above is also used for estimating the range to an aircraft target to assist in making a launch decision and to avoid launching when the target is out of range.
The STINGER is very effective during daylight hours against both fixed wing and rotary wing targets, and has even been used successfully by third world "freedom fighters" with limited formal training in the operation and use of the system. Presently, the STINGER missile system does not have a night vision optical sight for acquisition and identification of aircraft targets. Utilization of the missile system is therefore severely restricted during the night time because of the need to positively identify targets before launch, particularly when friendly aircraft are also in the area. At night, even when no friendly aircraft are present, the gunner can only use his ears and the missile infrared sensor in a usually futile attempt to "lock-on" to an aircraft, which would typically be moving at a high rate of speed. This results in greatly reduced capability for the STINGER system during hours of darkness.
The U.S. military employs a number of fielded night vision weapon sights, such as, the AN/PVS-4 Individual Served Weaponsight for aiming rifles and other projectile weapons. The problem with the AN/PVS-4 sight is that it has insufficient field of view to implement the STINGER firing sequence with the required elevation and lead angle. The, AN/PVS-4 has a 14 degree circular field of view, whereas a minimum of about 22 degrees is required for a sight designed for the STINGER. The small field of view also inhibits the search for aircraft targets, requiring a longer period of time to search a given search area.